I would appreciate input on the general idea of crawl space encapsulation & things to look out for as well.
Our house has a half basement ~1400 ft2 & half crawl space ~1300 ft2. You can walk upright in the crawl space so access is good. It's not monolithic as the hollow block wall & 4000psi concrete slab are separate. Would it have been beneficial to use 5000 psi concrete (waterproof)? Anyway, the trench in the area between the crawl space & basement (where the wall of separation is located) is subject to water infiltration after heavy rains. I assume this is from an increase in the water table. The "fix" for the previous decade has been a 1/2 HP Zoeller pump with 2" PVC pipe ~ 60' away. However, this isn't the optimal solution for several reasons. One is that I don't want standing water even where the pump is as that creates too much moisture in the crawl space area. I don't have a good backup system for when the primary pump fails.
There are 3 main contractors in my area that are viewed as doing it right for quite some time now (wished I had known when we built the house 10 years ago).
Contractor A: $13,650
Contractor B: $7,800 (used to work for Contractor A)
Contractor C: No return call although it's possible that I provided a bad number but they do have my email address. Giving them another chance this week but red flag already.
I would also appreciate any particular advice on the subsystems below. Interior drain system
around the crawl space interior perimeter:
Both use NDS EZflow
which is a gravel free French drain, i.e., fabric, lightweight gravel substitute, and pipe all in one package. It is made of 3 or 4 slotted corrugated pipe, surrounded by NDS poly-rock, and wrapped in a geotextile fabric. The NDS French Drain has been designed to take water out of the soil and pipe it to a safe discharge point. Encapsulation
: along floor & up concrete wall afixed with butyl tape, fasteners with washers, & adhesive leaving a 4-6" gap at the top for pest control
Contractor A: Basement Systems
CleanSpace 20-mil moisture barrier
Contractor B: WhiteCap
20-mil moisture barrier
Foundation vent covers will also be installed like this from Basement Systems Sump pump
: Plumbed separately to outside following slope of land ~ 30' away from house
Zoeller 1/3 & 1/2 hp backup sump pumps vs. Liberty 1/2 HP sump pumps Pro Series model ST1050
Contractor A: Basement Systems
Triple Safe (TSL) basin with lid but won't use the battery backup as the pumps are backed up by a propane generator
Contractor B: 24" diameter by 36" deep plastic sump pump basin with lidDehumidifier
: Plan is to place one in the basement & duct to the crawl space with separate hygrometers to see if that can handle both areas (rated for 2,900 ft2 so possible). If not, then I can add another smaller one to the crawl space.
Contractor A: SaniDry XP vs. AprilAire 1870F
Contractor B: Sante Fe Classic vs. Sante Fe Force
I don't see any point in insulating the basement walls as I'm in northern Alabama which neither contractor suggested.
Contractor A also wants to sell a $350 EverLast
PVC plastic door to better separate the crawl space & basement. However, I think that seems to be a waste as both areas should have the same environment once the crawl space is encapsulated.